Australian solar and battery guide
What size home battery makes sense in Australia?
The right battery size is the one your home can charge and use often enough to justify its extra cost. A large headline capacity alone does not answer that question.
By Solvetted · Reviewed · General information
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Start with the energy you can actually shift
Look at electricity imported after solar generation falls and the solar electricity available to charge a battery. A bill shows totals over a period; it usually cannot reveal the precise times you imported or exported. Interval meter and inverter data can make this comparison more useful.
If you already have solar, grid imports are only the electricity bought from the grid. They are not your home's total use, because some solar may have been consumed directly.
Compare usable capacity and output
Capacity is measured in kilowatt-hours (kWh): how much energy a battery can hold. Power output is measured in kilowatts (kW): how quickly it can supply that energy. Ask for usable capacity, rated output, round-trip efficiency, warranty terms and the loads that any backup configuration would support.
A battery can only save the grid electricity it actually displaces. If a larger unit rarely fills or empties, its extra capacity may bring little extra value. Compare each size with the same tariff and usage assumptions.
Price the extra step, not just the whole system
Compare a smaller battery with keeping your current setup, then compare a larger battery with the smaller one. Divide the extra installed cost by the extra annual benefit for a simple incremental payback. Treat that as a screening measure: it omits financing, degradation, maintenance and future tariff changes.
Federal certificate support changed on 1 May 2026 and tapers by usable-capacity band. Do not assume that every additional kilowatt-hour receives the same incentive. Request an itemised installed quote and check the current program rules for the proposed installation date.
Start with your home
Find your best-value size.
Postcode and bill are enough. See every size from 5 to 30 kWh and where extra capacity stops paying.